Components

• What do we need to draw circuit diagrams?

  Knowledge of components and their symbols
• Why do we need a cell or battery in a circuit?

  To provide electric power to the circuit
• What is the function of a switch in a circuit?

  To control the flow of electricity
• What happens when a switch is open?

  The circuit is effectively turned off
• What are filament lamps?

  Small bulbs used in circuits
• What is the purpose of a fuse in a circuit?

  To break the circuit if too much current flows
• What is a diode's function in a circuit?

  To allow current to flow in one direction
• What is a light emitting diode (LED)?

  A diode that emits light when current flows
• Where are LEDs commonly used?

  In alarm clocks and traffic lights
• What do ammeters measure in a circuit?

  Current
• How are ammeters connected in a circuit?

  In series
• What do voltmeters measure in a circuit?

  Potential difference
• How are voltmeters connected in a circuit?

  In parallel
• What are resistors used for in a circuit?

  To provide resistance
• What are the two types of basic resistors?

  Fixed and variable resistors
• What is a light dependent resistor (LDR)?

  A resistor whose resistance depends on light intensity
• How does an LDR behave in bright light?

  It has very low resistance
• What happens to an LDR's resistance in darkness?

  Resistance is very high
• How can LDRs be used in automatic night lights?

  They detect light and adjust resistance
• What is a thermistor?

  A resistor whose resistance depends on temperature
• How does the resistance of a thermistor change with temperature?

  Higher temperatures cause resistance to fall
• Where are thermistors commonly used?

  In car engines and electronic thermostats
• What are the main components and symbols used in circuit diagrams?

  • Cell or battery: provides power
  • Switch: controls electricity flow
  • Filament lamp: small bulb
  • Fuse: breaks circuit with excess current
  • Diode: allows current in one direction
  • LED: emits light when current flows
  • Ammeter: measures current in series
  • Voltmeter: measures potential difference in parallel
  • Resistors: provide resistance (fixed or variable)
  • LDR: resistance depends on light intensity
  • Thermistor: resistance depends on temperature